Solenoid actuated circuit breaker operator

ABSTRACT

A circuit breaker operating mechanism is provided having a frame mountable upon the face of a circuit breaker. A saddle assembly engages the operating handle of the circuit breaker and is slideably attached to the frame. A pair of solenoids are transversely mounted at opposite ends of the frame and are linked to the saddle assembly by two pairs of core and lever arm assemblies making lost motion connections to the saddle assembly. Energization of either solenoid applies force through the core and lever arm assemblies to the saddle assembly in a direction parallel to the direction of movement of the saddle assembly at points spaced away from the centerline of the saddle assembly.

" United States Patent Salvati et al. 1 July 1, 1975 1 SOLENOID ACTUATED CIRCUIT BREAKER 3,753,173 8/1973 Goldberg 335/1 OPERATOR P k E H m B rzmary xammeraro roome [75] Inventors gi g g f g {,Z Rlccl both Attorney, Agent, or FirmW. A. Elchik [73] Assi nee: Westinghouse Electric Corp., [57] ABSTRACT pmsburgh' A circuit breaker operating mechanism is provided [22] Filed; May 5 74 having a frame mountable upon the face of a circuit breaker. A saddle assembly engages the operating PP N05 470,104 handle of the circuit breaker and is slideably attached to the frame. A pair of solenoids are transversely 521 US. Cl. 335/1; 335/69; 335/184 mounted at Opposite ends of the frame and are linked 511 1m. 01. H01h 3/02 to the saddle assembly y two pairs of core and lever [58] Field f Search n 335 ll, 2, 69, 163, 177 arm assemblies making lost motion connections to the 35 saddle assembly. Energization of either solenoid applies force through the core and lever arm assemblies [56] References Cited to the saddle assembly in a direction parallel to the di- UNITED STATES PATENTS rection of movement of the saddle assembly at points 2 171 2 8/1939 D t 335,168 spaced away from the centerline of the saddle assemy 3,296,565 1/1967 Kiesel et al. 335/69 y 3,697,905 10/1972 Athans, Jr 335/1 8 Claims, 12 Drawing Figures Q,- =ll= (3117- 1 "Ai 49b 7 l 1 4 -=-q=% =4 p I" [I 7 I: 600

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1 SOLENOID ACTUATED CIRCUIT BREAKER OPERATOR BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates in general to operators for circuit breakers and more particularly to external operators with solenoid driven mechanisms.

2. Description of the Prior Art In many applications it is desirable to operate circuit breakers from a remote location. The breaker may be located in an inaccessible or out of the way location, or many circuit breakers may be required to be operated from one central station. One means for accomplishing this is to use a motor to drive a mechanism for actuating the circuit breaker. However these motor driven operating mechanisms often require gear trains and other complex components. The cost and maintenance requirements of such mechanisms render them impractical for smaller breakers. In addition, the time required for a motor to drive the mechanism to an extent necessary to actuate the circuit breaker is often objectionable.

Many of these problems can be alleviated by using a solenoid to drive a mechanism for operating the circuit breaker. The solenoid mechanism is simpler, cheaper, and requires less maintenance than a comparable motor driven mechanism. In addition solenoids can operate much more rapidly. However, the very speed of a solenoid driven mechanism often presents a problem, for in rapidly actuating a circuit breaker the shock created by such operation is often sufficient to damage or break the operating handle of the breaker. Thus, it is desirable to achieve high speed operation of the circuit breaker while at the same time protecting against damaging shock.

In many applications it is desirable to have a circuit breaker operator which can be removed from its associated circuit breaker and mounted upon another circuit breaker of the same or similar type. The mechanism for such an operator must be compact, especially for actuating small circuit breakers, but must produce sufficient force and throw movement to actuate such circuit breakers.

SUMMARY OF THE INVENTION The invention provides an operating mechanism for remotely controlling a circuit breaker. The mechanism includes a frame mountable in association with the circuit breaker and a saddle assembly engaging the operating handle of the associated circuit breaker. The saddle assembly is movably supported by the frame and actuates the operating handle of the circuit breaker from one operating position to another. Solenoid means are provided including core means and means for energizing the solenoid means to cause the core means to move from one operating position to another. Linkage means connecting the saddle assembly and the core means transmits force from the core means to the saddle assembly through lost motion connections at a plurality of points spaced away from the centerline of the saddle assembly, causing the saddle assembly to move the operating handle of the associated circuit breaker from one operating position to another in response to movement of the core means. By applying the force to the saddle assembly at points spaced away from the centerline of the saddle assembly, throw movement sufficient to operate the circuit breaker is obtained with a compact mechanism. The transmission of force through the linkage mechanism and the saddle assembly rather than directly to the operating handle of the circuit breaker provides shock absorbing capability preventing damage to the circuit breaker handle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the circuit breaker operating mechanism mounted upon the face of a circuit breaker;

FIG. 2 is a perspective view of the circuit breaker operating mechanism with the indicator flag removed and with the cover, limit switch assembly, and guide rail partially cut away;

FIG. 3 is a perspective view of the circuit breaker operating mechanism with the cover, limit switch assembly, and actuator assembly removed and with selonoids and frame partially cut away to show the construction of the core, lever arm, and saddle assemblies;

FIGS. 4, 5 and 6 are front elevational views partially cut away to show the core, lever arm, and saddle assemblies and the indicator flag positions when the operating mechanism is in open, tripped, and closed positions respectively;

FIGS. 7, 8 and 9 are side elevational views partially cut away to show the operation of the limit switch and actuator assemblies when the operating mechanism is in open, tripped, and closed position, respectively;

FIG. 10 is a side elevational view of the operating mechanism and associated circuit breaker showing the operating mechanism swung upward in a disengaged position;

FIG. 11 is a schematic wiring diagram showing the electrical connections to the operating mechanism when operated from a direct current supply; and

FIG. 12 is a schematic wiring diagram showing the electrical connections to the operating mechanism when operated from an alternating current supply.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, in FIG. 1 there is shown a perspective view of a circuit breaker operating mechanism 10 constructed according to the principles of the present invention. A frame 12 is constructed of high permeability magnetic material, such as ingot iron. Guide rails 14 are mounted along each side of the frame 12, each guide rail including a longitudinal slot 16. Riding in these slots 16 is a saddle assembly 18 consisting of a base 20 and side elements 22. Roller rods 24, 26 extend transverse to the saddle assembly through each side element 22 and through the longitudinal slots 16 in each of the side rails 14. The roller rods 24, 26 are secured in the slots 16 by C-rings 28. The saddle assembly 18 also includes two pairs of transverse slots 32, 34 shown more clearly in FIG. 3 and a holding structure consisting of two handle pins 38, as shown in FIGS. 7, 8 and 9. At opposite ends of the frame 12 are mounted a pair of solenoids 40, 42 parallel to each other and transverse to the frame l2. These solenoids are wound upon nylon bobbins 44, 46 shown in FIG. 3 which are held by the frame 12 thus attaching the solenoids to the frame 12.

The interior of each bobbin 44, 46 is a cylindrical volume containing two movable cores 48a and 48b, 50a and 5012 made of high permeability magnetic material.

These cores are free to slide within the interior of the bobbins 44, 46. When the cores 48a and 48b are positioned at the outer extremity of the interior of the bobbin 44 as shown in the upper solenoid 40 of FIG. 6, they define a working air gap 52.

As shown in FIG. 4, each core 48a and 48b, 50a and 50b is pivoted to a lever arm 56a and 56b, 58a and 58b by means ofa pin 49a and 49b, 51a and 51b. Each lever arm is also pivoted to the frame 12 by means of hex pins 60a and 60b, 62a and 62b. The end of each lever arm which is opposite the pivot pin 49a and 49b, 51a and 51b has attached to it an engaging pin 68, 70. Each engaging pin extends through one of the transverse slots 32, 34 in the saddle assembly 18 forming lost motion connections between the lever arms and the saddle assembly.

In FIG. 2 there is shown a limit switch assembly consisting of a limit switch 74 attached to a sheet metal switch mounting bracket 78 secured to the frame 12 by means of screws 45. The limit switch 74 is activated by movement of a plunger 76 which extends through the limit switch in a direction parallel to movement of the saddle assembly.

FIG. 7 shows a support column 82 attached to the base of the saddle assembly. This support column extends slightly above the frame 12 but not touching the limit switch mounting bracket 78. A U-shaped actuator bracket 86 of sheet metal is attached to the top of the support column 82. Flat-head pins 88, 90 extend through each end of the U-shaped bracket with their heads facing inward, cooperating with the plunger 76 of the limit switch 74. These pins are adjustably shock mounted to the U-shaped bracket by means of springs 92, 93 and nuts 94 which engage the threaded shaft of the flat-head pins 88, 90.

A cover 104, shown in FIG. 1, formed of sheet metal is removably attached to the operating mechanism 10 by screws engaging support posts 103. These posts are secured to the frame 12 by the engagement of threaded ends 122 of the post 103 in holes tapped into the frame 12, as in FIG. 7.

The hex pins 60a, 60b and 62a, 62b extend through holes 126 in the cover 104. An indicator flag 106 is affixed to hex pin 60a as shown in FIG. 4. Inscribed upon the indicator flag 106 are the words ON, OFF, and TRIP. As the saddle assembly 18 moves from its upper position, as in FIG. 6, corresponding to a breaker state of ON through an intermediate position, as in FIG. 5, corresponding to a tripped condition of the breaker to its lower position, shown in FIG. 4, corresponding to an OFF position of the breaker, the hex pin 60a rotates in the frame 12. The angular displacement of the hex pin 60a as the breaker moves between its various operational states causes the corresponding legend inscribed on the indicator flag 106 to be visible from the outside of the cover 104 through a window 105 cut into the sheet metal cover 104. Thus it is possible for an observer to determine the operational state of the associated breaker 108 without removing the cover.

In operation the mechanism is associated with a circuit breaker 108 having a molded case 110 and an operating handle 112, such as the type KB breaker. As shown in FIG. 1, the mechanism 10 is mounted upon the face 114 of the circuit breaker case 110. Screws 116 are used to secure the mechanism to mounting brackets 118 affixed to the case of the breaker 108 the brackets 118 are best shown in FIG. 2. In mounting the mechanism the saddle assembly 18 is positioned so that the handle pins 38 of the holding structure straddle the operating handle 112 of the breaker 108, as shown in FIGS. 7, 8 and 9.

In FIGS. 6 and 9 the saddle assembly is shown at the upper extremity of its travel. With the saddle assembly in this position the upper lever arms 56a and 56b are situated so that their engaging pins 68 are at the outer extremities of the upper transverse slots 32 of the saddle assembly. Also the cores 48a and 48b of the upper solenoid 40 are at the outer extremity of the bobbin 44. The working air gap 52 is thus at its largest size.

In contrast, the engaging pins of the lower lever arms 58a and 58b are at the inner extremities of the lower transverse slots 34 of the saddle assembly. The cores 50a and 50b of the lower solenoid 42 are correspondingly positioned in contact. with one another in the interior of the space within the lower bobbin 46. The working air gap 54 of the lower solenoid 42 is effectively eliminated.

Energization of the upper solenoid 40 produces a strong magnetic field within the interior of the bobbin 44 upon which it is wound. This field exerts force upon the movable cores 48a and 48b or the upper solenoid 40 drawing them toward one another within the interior of the bobbin 44. As the cores 48a and 48b approach one another, the upper lever arms 56a and 56b pivot about the hexagonal pins 60a and 60b transmitting force to the engaging pins 68 which in turn exert a downward force upon the saddle assembly 18. As the cores 48a and 48b continue to move toward the center of the bobbin, the lever arms and hexagonal pins continue to rotate within the frame 12 and the saddle assembly 18 travels downward, assuming successively the positions shown in FIGS. 5 and 4. As the saddle assembly 18 moves downward it exerts force on the lower engaging pins 70 which in turn cause the lower lever arms 58a and 58b and the hexagonal pins 62a and 62 b to pivot and drive the movable cores 50a and 50b of the lower solenoid 42 to the outer ends of the lower bobbin 46. Since the operating handle 112 of the circuit breaker 108 is engaged by the holding structure 36, as the saddle assembly 18 travels downward the operating handle also travels downward actuating the circuit breaker to a new operational state.

As the saddle assembly 18 moves downward, the attached support column 82 and actuator bracket 86 also move downward, as shown in FIGS. 9, 8 and 7. The flat-head pin 88 comes in contact with the limit switch plunger 76 depressing the plunger and actuating the limit switch 74. The spring 92 and nuts 84 are adjusted in such a manner that sufficient force to move the plunger 76 and operate the limit switch is produced when the saddle assembly 18 has moved a distance sufficient to move the operating handle 112 of the breaker 108 to a new operational state. The spring 92 also serves to absorb shock and prevent damage to the plunger 76. Actuation of the limit switch serves to deenergize the solenoid 40. At this point the operating mechanism 10 has succeeded in transferring the associated circuit breaker 108 from one operational state to another.

With the operating mechanism 10 engaged upon a circuit breaker 108 and the breaker in the OFF condition the saddle assembly 18 is in the position as shown in FIG. 4. To operate the breaker from the OFF position to the ON position, the ON switch 98, FIG. 11, is

actuated. This results in voltage being applied to the lower solenoid 42. Magnetic fluxis thereby produced with flows in the magnetic circuit defined by the air gap 52, the cores 50a and 501;, the side members 11 of the frame l2 and the cross members 13 of the frame 12. This flux produces a strong attractive force between the cores 50a and 50b acting across the air gap 54. This force causes the cores 50a and 50b to move toward the center of the bobbin 46 and toward one another, causing rotationof the lever arms 58a and 58b and the hex pins 62a and 62b. As the lever arms 58a and 58b rotate, the attached engaging pins 70 act against the saddle assembly l8 driving the saddle assembly 18 upward toward the position shown in FIG. 6. Since the operating handle 112 of the circuit breaker 108 is engaged by the handle pins 38 it also is moved, thus actuating the circuit breaker 108 to the ON state. As the saddle assembly 18 moves upward, force is applied to the engaging pins 68 causing rotation of the lever arms 56a and 56b, driving the cores 48a and 48b to the outer extremities of the bobbin 44, and rotating the hex pins 60a and 60b. The pin 60a rotates the indicator flag 106, causing the word ON to become visible through the window 105 in the cover 104. As the saddle assembly 18 travels upward the attached support column 82 and actuator assembly 84 also move upward. When the saddle assembly reaches the. upper extremity of its travel, the flat-head pin 90 comes in contact with the plunger 76 of the limit switch 74. The plunger is driven upward, actuating the limit switch and opening the circuit supplying electrical energy to the solenoid 42. It can be seen that the selective alternate energization of the solenoids 40 and 42 will result in transferring of the associated circuit breaker from one operational state to another operational state.

FIG. 11 is a diagram showing electrical connections which may be used to operate the mechanism. A power source supplying 125 volts DC is applied to the input terminals 96. Two switches 98 and 100 are connected as shown to provide for alternate energization of the two solenoids 40 and 42. These switches are preferably of the momentary contact pushbutton type. The limit switch 74 is connected as shown between the ON and OFF switches 98 and 100 and the two solenoids 40 and 42. With the limit switch in the position as shown in FIG. 11 the saddle assembly is in the OFF position or the lower position as shown in FIG. 6. In order to transfer the mechanism and the associated breaker from OFF position to the ON position, that is, to move the saddle assembly 18 to its upper position as shown in FIG. 4, the ON switch 98 is depressed. As can be seen in FIG. 11 this applies 125 volts DC to the ON solenoid 42. This action results in a magnetic field being produced in the ON solenoid 42 causing the movable core 50a and 50b to move toward the center of the bobbin 46. The lever arms 58a and 58b and hex pins 62a and 62b rotate, driving the saddle assembly 18 to its upper position. This results in movement of the actuator bracket 86 causing flathead pin 90 to come in Contact with the plunger 76 and actuate the limit switch 74 to its alternate position A in FIG. 11. The power supply is no longer connected to the ON solenoid 42.

The mechanism can also be operated from an AC power source as shown in FIG. 12. The only requirement is the addition of full wave rectifier bridge circuits 120a and 1201? connected as shown FIG. 12. These circuits serve to transform the alternating current to direct current in a well known manner and apply the direct current to the solenoids 40 or 42.

The mechanism may also be operated from a higher voltage supply source by the addition of a suitable resistor 102 as shown in FIGS. 11 and 12. The value of the resistor will depend on the voltage of the power source from which it is desired to operate the mechanism and the impedance of the solenoids 40 and 42. For example, if it is desired to operate the mechanism from a 250 volt DC supply the resistance value of the resistor 102 .should be equal to the resistances of the solenoids 40 and 42. Correspondingly, if it is desired to operate the mechanism from a 240 volt AC supply a resistor should be chosen with an impedance equal to the impedances of the solenoids 40 and 42.

Manual operation of the circuit breaker can be accomplished with the operating mechanism 10 in place by the action of a pair of wrench levers 126 and 127, FIG. 1. Each lever includes a hexagonal shaped hole which is fitted over the hex pins 60a or 60b. Lever 126 includes a pin extending perpendicular to the plane of the levers 126 and 127 through a corresponding slot 128 in lever 127. Applying manual force to the pin 130 in an upward or downward direction results in the rotation of hex pins 62a and 62b. This in turn causes movement of the lever arms 56a and 56b transmitting motion to the saddle assembly 18 and actuating the circuit breaker 108.

The operating mechanism 10 can be easily removed from the associated circuit breaker 108 by removing the four screws 116 and lifting the operating mechanism away from the face of the circuit breaker. Alternatively, the mechanism can be temporarily disengaged from the circuit breaker by removing the bottom two of the screws 116 and swinging the mechanism upward and away from the face of the breaker as is shown in FIG. 10.

A requirement of an operating mechanism for smaller molded case circuit breakers is that the structure be compact. In the present mechanism compactness of design is achieved by providing that force be transmitted from the lever arms to the saddle assembly at a point which ensures maximum linear travel of the saddle assembly 18. This is done by extending the transverse slots 32 and 34 laterally to the extreme edge of the saddle assembly 18 with respect to the centerline of the saddle assembly.

The base member 20 of the saddle assembly lies in a plane substantially parallel to the circuit breaker face 114. However, it has a natural tendency to rock out of this plane as the saddle assembly 18 moves from one extreme of its travel to the other. This is due to the action of the slanted faces of the circuit breaker operating handle 1 12 upon the handle pins 38 of the holding structure. Any excessive rocking motion would tend to cause mechanical binding of the saddle assembly with respect to the frame and preventing motion of the saddle assembly 18. This rocking motion is prevented by the transverse rods 24 and 26 which act as roller bear ings in the longitudinal slots 16 of the side rails 14.

The build-up of force upon energization of a solenoid is extremely rapid, causing a correspondingly high acceleration of the cores 48a, 48b or 50a, 50b. The lever arms 56a, 56b and 58a, 58b and the connections between these lever arms and the cores and the saddle assembly 18 serve to absorb the shock of the rapid acceleration thereby preventing damage to the circuit breaker operating handle 112. They perform a similar function when the saddle assembly 18 reaches the end of its travel. As the core pairs meet inside their respective bobbins additional shock is absorbed that might be directed on the breakers operating handle.

it will be seen therefore that there has been disclosed an operating mechanism for molded case circuit breakers which is of compact design and simple construction.

We claim as our invention:

1. An operating mechanism for remotely controlling a circuit breaker, said operating mechanism comprismg:

a. a frame mountable in association with a circuit breaker, said circuit breaker having an operating handle,

b. a saddle assembly adapted to engage the operating handle of the associated circuit breaker, said saddle assembly activating the operating handle of the circuit breaker upon movement of said saddle assembly,

c. means attached to said frame for supporting said saddle assembly, said saddle assembly supporting means permitting linear longitudinal movement of said saddle assembly with respect to said frame through sufficient distance to actuate the associated circuit breaker operating handle from one operating position to another operating position,

d. solenoid means, said solenoid means comprising movable core means,

e. means for energizing said solenoid means to cause said core means to move from one operating position to another operating position; and,

f. linkage means connecting said saddle assembly and said core means, said linkage means transmitting force from said core means to said saddle assembly through lost motion connections at a plurality of points spaced away from the centerline of said saddle assembly, said saddle assembly moving said breaker handle from one operating position to another operating position in response to movement of said core means.

2. An operating mechanism as described in claim 1, wherein said solenoid means comprises two solenoids having movable cores, said solenoids being disposed in parallel at opposite ends of said frame, and transverse to said frame.

3. An operating mechanism as described in claim 1, wherein said support means comprises a pair of guide rails disposed on opposite sides of said frame, each of said guide rails including a longitudinal slot parallel to the direction of movement of said saddle assembly.

4. An operating mechanism as described in claim 3, wherein said saddle assembly comprises a generally U- shaped saddle member including a base element and two projecting side elements, said base element having a plurality of transverse slots and a holding structure, said holding structure being adapted to engage the operating handle of a circuit breaker, said saddle assembly having a plurality of transverse rods, each of said rods projecting through both of said side elements and each of said transverse rods being slidably attached to said guide rails through said longitudinal slots.

5. An operating mechanism as described in claim 4, wherein said linkage means comprises four lever arms, each of said lever arms being pivoted at one end thereof to one of said movable cores; each of said lever arms being provided at another end with a pin, said pin engaging one of said transverse slots of said saddle assembly, to provide lost motion connections to said saddle assembly and to transmit force to said saddle assembly in a direction parallel to the direction of movement of said saddle assembly, said force being applied at points spaced away from the centerline of said saddle assembly; and each of said lever arms being pivotally attached intermediate their two ends to said frame.

6. An operating mechanism as in claim 1, wherein said frame is removably mountable upon the face of a circuit breaker.

7. An operating mechanism as in claim 1, wherein a limit switch is provided to deenergize said solenoid means.

8. An operating mechanism as in claim 7, wherein a limit switch actuating means is attached to said saddle assembly, said limit switch actuating means being operative to actuate said limit switch when said saddle assembly has moved a sufficient distance to actuate the handle of an associated circuit breaker to a selected operating position. 

1. An operating mechanism for remotely controlling a circuit breaker, said operating mechanism comprising: a. a frame mountable in association with a circuit breaker, said circuit breaker having an operating handle, b. a saddle assembly adapted to engage the operating handle of the associated circuit breaker, said saddle assembly activating the operating handle of the circuit breaker upon movement of said saddle assembly, c. means attached to said frame for supporting said saddle assembly, said saddle assembly supporting means permitting linear longitudinal movement of said saddle assembly with respect to said frame through sufficient distance to actuate the associated circuit breaker operating handle from one operating position to another operating position, d. solenoid means, said solenoid means comprising movable core means, e. means for energizing said solenoid means to cause said core means to move from one operating position to another operating position; and, f. linkage means connecting said saddle assembly and said core means, said linkage means transmitting force from said core means to said saddle assembly through lost motion connections at a plurality of points spaced away from the centerline of said saddle assembly, said saddle assembly moving said bReaker handle from one operating position to another operating position in response to movement of said core means.
 2. An operating mechanism as described in claim 1, wherein said solenoid means comprises two solenoids having movable cores, said solenoids being disposed in parallel at opposite ends of said frame, and transverse to said frame.
 3. An operating mechanism as described in claim 1, wherein said support means comprises a pair of guide rails disposed on opposite sides of said frame, each of said guide rails including a longitudinal slot parallel to the direction of movement of said saddle assembly.
 4. An operating mechanism as described in claim 3, wherein said saddle assembly comprises a generally U-shaped saddle member including a base element and two projecting side elements, said base element having a plurality of transverse slots and a holding structure, said holding structure being adapted to engage the operating handle of a circuit breaker, said saddle assembly having a plurality of transverse rods, each of said rods projecting through both of said side elements and each of said transverse rods being slidably attached to said guide rails through said longitudinal slots.
 5. An operating mechanism as described in claim 4, wherein said linkage means comprises four lever arms, each of said lever arms being pivoted at one end thereof to one of said movable cores; each of said lever arms being provided at another end with a pin, said pin engaging one of said transverse slots of said saddle assembly, to provide lost motion connections to said saddle assembly and to transmit force to said saddle assembly in a direction parallel to the direction of movement of said saddle assembly, said force being applied at points spaced away from the centerline of said saddle assembly; and each of said lever arms being pivotally attached intermediate their two ends to said frame.
 6. An operating mechanism as in claim 1, wherein said frame is removably mountable upon the face of a circuit breaker.
 7. An operating mechanism as in claim 1, wherein a limit switch is provided to deenergize said solenoid means.
 8. An operating mechanism as in claim 7, wherein a limit switch actuating means is attached to said saddle assembly, said limit switch actuating means being operative to actuate said limit switch when said saddle assembly has moved a sufficient distance to actuate the handle of an associated circuit breaker to a selected operating position. 